Bedaquiline, an FDA-approved antibiotic, inhibits mitochondrial function and potently blocks the proliferative expansion of stem-like cancer cells (CSCs)

OXPHOS inhibition overcomes chemoresistance in triple negative breast cancer

The hypothesis of a significant shift from oxidative phosphorylation (OXPHOS) to glycolysis in a number of solid tumors has been dominant for many years. Recently, however, evidence has begun to accumulate that OXPHOS is the major mode of energy production in many neoplasias, especially those that have undergone chemo- or radiotherapy, and especially in chemoresistant malignancies. In the present work, we demonstrated that chemoresistant triple-negative breast cancer cells prefer to obtain energy via OXPHOS to a greater extent than cells sensitive to chemotherapeutic agents, and therefore the former can be affected by some OXPHOS inhibitors. From a drug library containing several dozen antimicrobials, we selected those that inhibit OXPHOS in resistant TNBC cells and lead to mitochondrial dysfunction. We have also identified several pathways by which inhibition of growth suppression of chemoresistant cells occurs, including increased oxidative stress and mitophagy. Experiments in mice showed that selected OXPHOS inhibitors preferentially suppress tumor growth from chemoresistant but not from chemosensitive cells. The results of the present study suggest combinatorial therapy of such inhibitors and conventional anticancer drugs on resistant forms of tumors, if the latter show enhanced OXPHOS.

Targeting DNA helicase CMG complex and NFκB2-driven drug-resistant transcriptional axis to effectively treat KRASG12D-mutated pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a 5-year overall survival (OS) rate of approximately 12%. More than 90% of PDAC patients harbor oncogenic mutations in the Kirsten rat sarcoma viral homolog (KRAS) gene. MRTX1133 (MRTX), a novel inhibitor of KRASG12D (the most common KRAS mutation found in pancreatic and colon cancers) has shown promise as a therapeutic agent. To address reported resistance to MRTX, we adapted our anti-leukemia co-targeting strategy and evaluated a combination of MRTX and Bedaquiline (BED), an FDA-approved inhibitor of mitochondrial ATP production, in in vitro human PDAC models. The combination of MRTX and BED demonstrated enhanced cytotoxic effects by disrupting all 11 genes within the DNA helicase family (CMG complex: CDC45-MCM-GINS), which are essential for initiating DNA replication and regulating cell cycle progression. Notably, real-world data analysis from Caris Life Sciences and NCI-TCGA database revealed that low transcriptomic expression of the DNA helicase CMG complex was significantly associated with prolonged survival (e.g., low CDC45 expression and low GINS2 expression with greater than 8 months longer overall survival) in PDAC patients with KRASG12 mutations (N = 9,717; P < 0.00001). However, this combination therapy also triggered strong pro-survival nuclear reprogramming. This effect was mediated by significant genetic activation of an NFκB2-DDIT (DNA damage-induced transcript) axis, which supported tumor chromosomal integrity and DNA repair mechanisms. To overcome NFκB2-driven resistance mechanisms, we explored a triple-targeting strategy that addresses metabolic and genomic plasticity in addition to actively intercepting cell division. This approach combines MRTX1133, Bedaquiline, and the NFκB2 inhibitor SN52, offering a novel therapeutic avenue to treat aggressive pancreatic cancer and potentially improve patient outcomes.

Quinolines: A Promising Heterocyclic Scaffold for Cancer Therapeutics

The quinoline scaffold is a widely recognized heterocycle with applications across various disease categories, ranging from malaria and viral infections to bacterial infections, high cholesterol, and even tumors. Consequently, quinoline plays a crucial role in the development of new drugs, and the field greatly benefits from advancements in computer-aided drug design. This review aims to provide insights into the evolution of quinoline and its derivatives, offering a comprehensive exploration of both marketed and developing drugs. Furthermore, the function and mechanism of quinoline compounds are introduced. Many studies rely on cell experiments to demonstrate drug cytotoxicity. In the concluding section of this review, the interaction between quinoline compounds and targets is simulated using computer-aided drug design methods. A thorough analysis is conducted on the potential influencing factors affecting the binding state between quinoline compounds and targets. Notably, the Pi-Alkyl interaction emerges as a significant contributor, while hydrogen bonding is identified as a pivotal bond in these interactions. This review serves as a valuable overview of the potential contributions of quinoline compounds to cancer treatment. It seamlessly combines the essential functions of marketed quinoline drugs with the promise held by emerging quinoline-based compounds. Additionally, the simulation of interactions between quinoline compounds and proteins through computer-aided design enhances our understanding of these compounds' efficacy.

Fragment-based development of small molecule inhibitors targeting Mycobacterium tuberculosis cholesterol metabolism

Mycobacterium tuberculosis (Mtb) is the world's most deadly infectious pathogen and new drugs are urgently required to combat the emergence of multi- (MDR) and extensively- (XDR) drug resistant strains. The bacterium specifically upregulates sterol uptake pathways in infected macrophages and the metabolism of host-derived cholesterol is essential for Mtb's long-term survival in vivo. Here, we report the development of antitubercular small molecules that inhibit the Mtb cholesterol oxidases CYP125 and CYP142, which catalyze the initial step of cholesterol metabolism. An efficient biophysical fragment screen was used to characterize the structure-activity relationships of CYP125 and CYP142, and identify a non-azole small molecule 1a that can bind to the heme cofactor of both enzymes. A structure-guided fragment-linking strategy was used to optimize the binding affinity of 1a, yielding a potent dual CYP125/142 inhibitor 5m (KD CYP125/CYP142 = 0.04/0.16 μM). Compound 5m potently inhibits the catalytic activity of CYP125 and CYP142 in vitro (KI values < 0.1 μM), and rapidly depletes Mtb intracellular ATP (IC50 = 0.15 μM). The compound has antimicrobial activity against both drug susceptible and MDR Mtb (MIC99 values 0.4 - 1.5 μM) in extracellular assays, and inhibits the growth of Mtb in human macrophages (MIC = 1.7 μM) with good selectivity over mammalian cytotoxicity (LD50 ≥ 50 μM). The combination of small molecule inhibitors and structural data reported here provide useful tools to study the role of cholesterol metabolism in Mtb and are a promising step towards novel antibiotics targeting bioenergetic pathways, which could be used to help combat MDR-TB.

Neuronal Cell Rearrangement During Aging: Antioxidant Compounds as a Potential Therapeutic Approach

Aging is a natural process that leads to time-related changes and a decrease in cognitive abilities, executive functions, and attention. In neuronal aging, brain cells struggle to respond to oxidative stress. The structure, function, and survival of neurons can be mediated by different pathways that are sensitive to oxidative stress and age-related low-energy states. Mitochondrial impairment is one of the most noticeable signs of brain aging. Damaged mitochondria are thought to be one of the main causes that feed the inflammation related to aging. Also, protein turnover is involved in age-related impairments. The brain, due to its high oxygen usage, is particularly susceptible to oxidative damage. This review explores the mechanisms underlying neuronal cell rearrangement during aging, focusing on morphological changes that contribute to cognitive decline and increased susceptibility to neurodegenerative diseases. Potential therapeutic approaches are discussed, including the use of antioxidants (e.g., Vitamin C, Vitamin E, glutathione, carotenoids, quercetin, resveratrol, and curcumin) to mitigate oxidative damage, enhance mitochondrial function, and maintain protein homeostasis. This comprehensive overview aims to provide insights into the cellular and molecular processes of neuronal aging and highlight promising therapeutic avenues to counteract age-related neuronal deterioration.

Drug Repurposing for Cancer Treatment: A Comprehensive Review

Cancer ranks among the primary contributors to global mortality. In 2022, the global incidence of new cancer cases reached about 20 million, while the number of cancer-related fatalities reached 9.7 million. In Saudi Arabia, there were 13,399 deaths caused by cancer and 28,113 newly diagnosed cases of cancer. Drug repurposing is a drug discovery strategy that has gained special attention and implementation to enhance the process of drug development due to its time- and money-saving effect. It involves repositioning existing medications to new clinical applications. Cancer treatment is a therapeutic area where drug repurposing has shown the most prominent impact. This review presents a compilation of medications that have been repurposed for the treatment of various types of cancers. It describes the initial therapeutic and pharmacological classes of the repurposed drugs and their new applications and mechanisms of action in cancer treatment. The review reports on drugs from various pharmacological classes that have been successfully repurposed for cancer treatment, including approved ones and those in clinical trials and preclinical development. It stratifies drugs based on their anticancer repurpose as multi-type, type-specific, and mechanism-directed, and according to their pharmacological classes. The review also reflects on the future potential that drug repurposing has in the clinical development of novel anticancer therapies.

Mitochondrial bioenergetics of breast cancer

Breast cancer cells exhibit metabolic heterogeneity based on tumour aggressiveness. Glycolysis and mitochondrial respiration are two major metabolic pathways for ATP production. The oxygen flux, oxygen tension, proton leakage, protonmotive force, inner mitochondrial membrane potential, ECAR and electrochemical proton gradient maintain metabolic homeostasis, ATP production, ROS generation, heat dissipation, and carbon flow and are referred to as "sub-domains" of mitochondrial bioenergetics. Tumour aggressiveness is influenced by these mechanisms, especially when breast cancer cells undergo metastasis. These physiological parameters for healthy mitochondria are as crucial as energy demands for tumour growth and metastasis. The instant energy demands are already elucidated under Warburg effects, while these parameters may have dual functionality to maintain cellular bioenergetics and cellular health. The tumour cell might maintain these mitochondrial parameters for mitochondrial health or avoid apoptosis, while energy production could be a second priority. This review focuses explicitly on the crosstalk between metabolic domains and the utilisation of these parameters by breast cancer cells for their progression. Some major interventions are discussed based on mitochondrial bioenergetics that need further investigation. This review highlights the pathophysiological significance of mitochondrial bioenergetics and the regulation of its sub-domains by breast tumour cells for uncontrolled proliferation.

Cellular senescence and metabolic reprogramming: Unraveling the intricate crosstalk in the immunosuppressive tumor microenvironment

The intrinsic oncogenic mechanisms and properties of the tumor microenvironment (TME) have been extensively investigated. Primary features of the TME include metabolic reprogramming, hypoxia, chronic inflammation, and tumor immunosuppression. Previous studies suggest that senescence-associated secretory phenotypes that mediate intercellular information exchange play a role in the dynamic evolution of the TME. Specifically, hypoxic adaptation, metabolic dysregulation, and phenotypic shifts in immune cells regulated by cellular senescence synergistically contribute to the development of an immunosuppressive microenvironment and chronic inflammation, thereby promoting the progression of tumor events. This review provides a comprehensive summary of the processes by which cellular senescence regulates the dynamic evolution of the tumor-adapted TME, with focus on the complex mechanisms underlying the relationship between senescence and changes in the biological functions of tumor cells. The available findings suggest that components of the TME collectively contribute to the progression of tumor events. The potential applications and challenges of targeted cellular senescence-based and combination therapies in clinical settings are further discussed within the context of advancing cellular senescence-related research.

Drug tolerant persister cell plasticity in cancer: A revolutionary strategy for more effective anticancer therapies

Non-genetic mechanisms have recently emerged as important drivers of anticancer drug resistance. Among these, the drug tolerant persister (DTP) cell phenotype is attracting more and more attention and giving a predominant non-genetic role in cancer therapy resistance. The DTP phenotype is characterized by a quiescent or slow-cell-cycle reversible state of the cancer cell subpopulation and inert specialization to stimuli, which tolerates anticancer drug exposure to some extent through the interaction of multiple underlying mechanisms and recovering growth and proliferation after drug withdrawal, ultimately leading to treatment resistance and cancer recurrence. Therefore, targeting DTP cells is anticipated to provide new treatment opportunities for cancer patients, although our current knowledge of these DTP cells in treatment resistance remains limited. In this review, we provide a comprehensive overview of the formation characteristics and underlying drug tolerant mechanisms of DTP cells, investigate the potential drugs for DTP (including preclinical drugs, novel use for old drugs, and natural products) based on different medicine models, and discuss the necessity and feasibility of anti-DTP therapy, related application forms, and future issues that will need to be addressed to advance this emerging field towards clinical applications. Nonetheless, understanding the novel functions of DTP cells may enable us to develop new more effective anticancer therapy and improve clinical outcomes for cancer patients.

Metabolic vulnerability of cancer stem cells and their niche

Cancer stem cells (CSC) are the leading cause of the failure of anti-tumor treatments. These aggressive cancer cells are preserved and sustained by adjacent cells forming a specialized microenvironment, termed niche, among which tumor-associated macrophages (TAMs) are critical players. The cycle of tricarboxylic acids, fatty acid oxidation path, and electron transport chain have been proven to play central roles in the development and maintenance of CSCs and TAMs. By improving their oxidative metabolism, cancer cells are able to extract more energy from nutrients, which allows them to survive in nutritionally defective environments. Because mitochondria are crucial bioenergetic hubs and sites of these metabolic pathways, major hopes are posed for drugs targeting mitochondria. A wide range of medications targeting mitochondria, electron transport chain complexes, or oxidative enzymes are currently investigated in phase 1 and phase 2 clinical trials against hard-to-treat tumors. This review article aims to highlight recent literature on the metabolic adaptations of CSCs and their supporting macrophages. A focus is provided on the resistance and dormancy behaviors that give CSCs a selection advantage and quiescence capacity in particularly hostile microenvironments and the role of TAMs in supporting these attitudes. The article also describes medicaments that have demonstrated a robust ability to disrupt core oxidative metabolism in preclinical cancer studies and are currently being tested in clinical trials.

The cubosome-based nanoplatforms in cancer therapy: Seeking new paradigms for cancer theranostics

Lyotropic liquid crystals are self-assembled, non-lamellar, and mesophase nanostructured materials that have garnered significant attention as drug carriers. Cubosomes, a subtype of lyotropic liquid crystalline nanoparticles, possess three-dimensional structures that display bicontinuous cubic liquid-crystalline patterns. These patterns are formed through the self-organization of unsaturated monoglycerides (amphphilic lipids such as glyceryl monooleate or phytantriol), followed by stabilization using steric polymers (poloxamers). Owing to their bicontinuous structure and steric polymer-based stabilization, cubosomes have been demonstrated to possess greater entrapment efficiency for hydrophobic drugs compared to liposomes, while also exhibiting high stability. In the past decade, there has been significant interest in cubosomes due to their ability to deliver therapeutic and contrast agents for cancer treatment and imaging with minimal side effects, establishing them as a safe and effective approach. Concerning these advantages, the present review elaborates on the general aspects, composition, and preparation techniques of cubosomes, followed by explanations of their mechanisms of drug loading and release patterns. Furthermore, the review provides meticulous discussions on the use of cubosomes in the treatment and imaging of various types of cancer, culminating in the enumeration of patents related to cubosome-based drug delivery systems.

Mitochondrial dysfunction at the crossroad of cardiovascular diseases and cancer

A large body of evidence indicates the existence of a complex pathophysiological relationship between cardiovascular diseases and cancer. Mitochondria are crucial organelles whose optimal activity is determined by quality control systems, which regulate critical cellular events, ranging from intermediary metabolism and calcium signaling to mitochondrial dynamics, cell death and mitophagy. Emerging data indicate that impaired mitochondrial quality control drives myocardial dysfunction occurring in several heart diseases, including cardiac hypertrophy, myocardial infarction, ischaemia/reperfusion damage and metabolic cardiomyopathies. On the other hand, diverse human cancers also dysregulate mitochondrial quality control to promote their initiation and progression, suggesting that modulating mitochondrial homeostasis may represent a promising therapeutic strategy both in cardiology and oncology. In this review, first we briefly introduce the physiological mechanisms underlying the mitochondrial quality control system, and then summarize the current understanding about the impact of dysregulated mitochondrial functions in cardiovascular diseases and cancer. We also discuss key mitochondrial mechanisms underlying the increased risk of cardiovascular complications secondary to the main current anticancer strategies, highlighting the potential of strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction and tumorigenesis. It is hoped that this summary can provide novel insights into precision medicine approaches to reduce cardiovascular and cancer morbidities and mortalities.

The tale of antibiotics beyond antimicrobials: Expanding horizons

Antibiotics had proved to be a godsend for mankind since their discovery. They were once the magical solution to the vexing problem of infection-related deaths. German scientist Paul Ehrlich had termed salvarsan as the silver bullet to treatsyphilis.As time passed, the magic of newly discovered silver bullets got tarnished with raging antibiotic resistance among bacteria and associated side-effects. Still, antibiotics remain the primary line of treatment for bacterial infections. Our understanding of their chemical and biological activities has increased immensely with advancement in the research field. Non-antibacterial effects of antibiotics are studied extensively to optimise their safer, broad-range use. These non-antibacterial effects could be both useful and harmful to us. Various researchers across the globe including our lab are studying the direct/indirect effects and molecular mechanisms behind these non-antibacterial effects of antibiotics. So, it is interesting for us to sum up the available literature. In this review, we have briefed the possible reason behind the non-antibacterial effects of antibiotics, owing to the endosymbiotic origin of host mitochondria. We further discuss the physiological and immunomodulatory effects of antibiotics. We then extend the review to discuss molecular mechanisms behind the plausible use of antibiotics as anticancer agents.

Structure-directed identification of pyridine-2-methylamine derivatives as MmpL3 inhibitors for use as antitubercular agents

Mycobacterial membrane protein Large 3 (MmpL3), an inner membrane protein, plays a crucial role in the transport of mycolic acids that are essential for the viability of M. tuberculosis and has been a promising therapeutic target for new anti-TB agents. Herein, we report the discovery of pyridine-2-methylamine antitubercular compounds using a structure-based drug design strategy. Compound 62 stands out as the most potent compound with high activity against M. tb strain H37Rv (MIC = 0.016 μg/mL) as well as the clinically isolated strains of MDR/XDR-TB (MIC = 0.0039-0.0625 μg/mL), low Vero cell toxicity (IC50 ≥ 16 μg/mL), and moderate liver microsomal stability (CLint = 28 μL/min/mg). Furthermore, the resistant mutant of S288T due to single nucleotide polymorphism in mmpL3 was resistant to pyridine-2-methylamine 62, demonstrating compound 62 is likely target to MmpL3.

High resveratrol-loaded microcapsules with trehalose and OSA starch as the wall materials: Fabrication, characterization, and evaluation

To improve the solubility and stability of resveratrol (Res), Res nanocrystals (Res-ncs) as the capsule core were prepared by wet milling using hydroxypropyl methyl cellulose (HPMC_E5), sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP_K30) as stabilizers, along with trehalose and octenyl succinic anhydride (OSA) modified starch were used as the wall material to produce Res microcapsules (Res-mcs) via spray drying. The fresh-prepared Res-ncs and rehydrated Res-mcs had mean particle sizes of 190.30 ± 3.43 and 204.70 ± 3.60 nm, zeta potentials of -13.90 ± 0.28 and - 11.20 ± 0.34 mV, and the loading capacities (LC) were as high as 73.03 % and 28.83 %. Particle morphology showed that Res-mcs had more regular and smooth spherical structures. FTIR indicated that Res may have hydrogen bonding with the walls. XRD and DSC exhibited that Res in nanocrystals and microcapsules existed mostly as amorphous structures. The solubility of Res-mcs and Res-ncs was increased, with excellent redispersibility and rapid dissolution of Res in vitro. The antioxidant properties of Res-mcs were protected and improved. With the walls acting as a physical barrier, Res-mcs have better photothermal stability than raw Res. Res-mcs have a relative bioavailability of 171.25 %, which is higher than that of raw Res.

Metabolic dependencies and targets in ovarian cancer

Reprogramming of cellular metabolism is a hallmark of cancer. Cancer cells undergo metabolic adaptations to maintain tumorigenicity and survive under the attack of immune cells and chemotherapy in the tumor microenvironment. Metabolic alterations in ovarian cancer in part overlap with findings from other solid tumors and in part reflect unique traits. Altered metabolic pathways not only facilitate ovarian cancer cells' survival and proliferation but also endow them to metastasize, acquire resistance to chemotherapy, maintain cancer stem cell phenotype and escape the effects of anti-tumor immune defense. In this review, we comprehensively review the metabolic signatures of ovarian cancer and their impact on cancer initiation, progression, and resistance to treatment. We highlight novel therapeutic strategies targeting metabolic pathways under development.

Targeting ATP Synthase by Bedaquiline as a Therapeutic Strategy to Sensitize Ovarian Cancer to Cisplatin

Cisplatin is a common chemotherapeutic drug for treating ovarian cancer, but its clinical efficacy is hampered by intrinsic and acquired resistance. Previous studies had shown inhibiting oxidative phosphorylation overcomes cisplatin resistance in ovarian cancer. Studies reveal that bedaquiline, a clinically available antimicrobial drug, inhibits cancer via targeting mitochondria. This study systematically assessed the efficacy of bedaquiline in ovarian cancer and its underlying mechanism. Using a panel of ovarian cancer cell lines and normal ovary cells, we demonstrated bedaquiline is selective for anti-ovarian cancer activities. Furthermore, the sensitivity varied among different ovarian cancer cell lines regardless of their sensitivity to cisplatin. Bedaquiline inhibited growth, survival and migration, through decreasing levels of ATP synthase subunit, complex V activity, mitochondrial respiration and ATP. We further found that ovarian cancer displayed increased levels of ATP, oxygen consumption rate (OCR), complex V activity and ATP synthase subunits compared to normal counterpart. Combination index analysis showed that bedaquiline and cisplatin is synergistic. Bedaquiline remarkably enhanced the efficacy of cisplatin in inhibiting ovarian cancer growth in mice. Our study provides evidence to repurpose bedaquiline for ovarian cancer treatment and suggests that ATP synthase is a selective target to overcome cisplatin resistance in ovarian cancer.

An overview of current strategies and future prospects in drug repurposing in tuberculosis

A large number of the population faces mortality as an effect of tuberculosis (TB). The line of treatment in the management of TB faces a jolt with ever-increasing multi-drug resistance (DR) cases. Further, the drugs engaged in the treatment of TB are associated with different toxicities, such as renal and hepatic toxicity. Different combinations are sought for effective anti-tuberculosis (anti-TB) effects with a decrease in toxicity. In this regard, drug repurposing has been very promising in improving the efficacy of drugs by enhancement of bioavailability and widening the safety margin. The success in drug repurposing lies in specified binding and inhibition of a particular target in the drug molecule. Different drugs have been repurposed for various ailments like cancer, Alzheimer’s disease, acquired immunodeficiency syndrome (AIDS), hair loss, etc. Repurposing in anti-TB drugs holds great potential too. The use of whole-cell screening assays and the availability of large chemical compounds for testing against Mycobacterium tuberculosis poses a challenge in this development. The target-based discovery of sites has emerged in the form of phenotypic screening as ethionamide R (EthR) and malate synthase inhibitors are similar to pharmaceuticals. In this review, the authors have thoroughly described the drug repurposing techniques on the basis of pharmacogenomics and drug metabolism, pathogen-targeted therapy, host-directed therapy, and bioinformatics approaches for the identification of drugs. Further, the significance of repurposing of drugs elaborated on large databases has been revealed. The role of genomics and network-based methods in drug repurposing has been also discussed in this article.

Bedaquiline fumarate microemulsion: formulation optimization, rheological characterization and in vitro studies

Aim: Bedaquiline fumarate (BQF), an antitubercular drug, shows limited bioavailability due to solubility-limited intestinal absorption. In this research, the authors formulated a BQF-loaded microemulsion to improve BQF's oral bioavailability. Methods: Microemulsion was prepared by a spontaneous emulsification method and evaluated for thermodynamic stability, size, dispersibility, transmittance, rheology, microrheology, drug release, cytotoxicity and cellular uptake. Results: Microemulsion showed an average globule size of 26.50 ± 6.29 nm with spherical geometry and revealed gel-sol-gel behavior in microrheological studies. Cytotoxicity and cell uptake studies in Caco-2 cells showed that BQF microemulsion was cytocompatible at the highest concentration of 500 μg/ml with significantly higher cellular uptake than control. Conclusion: The present study indicates that BQF microemulsion could be explored further for effective treatment of multidrug-resistant tuberculosis.

Mitochondrial mutations and mitoepigenetics: Focus on regulation of oxidative stress-induced responses in breast cancers

Epigenetic regulation of mitochondrial DNA (mtDNA) is an emerging and fast-developing field of research. Compared to regulation of nucler DNA, mechanisms of mtDNA epigenetic regulation (mitoepigenetics) remain less investigated. However, mitochondrial signaling directs various vital intracellular processes including aerobic respiration, apoptosis, cell proliferation and survival, nucleic acid synthesis, and oxidative stress. The later process and associated mismanagement of reactive oxygen species (ROS) cascade were associated with cancer progression. It has been demonstrated that cancer cells contain ROS/oxidative stress-mediated defects in mtDNA repair system and mitochondrial nucleoid protection. Furthermore, mtDNA is vulnerable to damage caused by somatic mutations, resulting in the dysfunction of the mitochondrial respiratory chain and energy production, which fosters further generation of ROS and promotes oncogenicity. Mitochondrial proteins are encoded by the collective mitochondrial genome that comprises both nuclear and mitochondrial genomes coupled by crosstalk. Recent reports determined the defects in the collective mitochondrial genome that are conducive to breast cancer initiation and progression. Mutational damage to mtDNA, as well as its overproliferation and deletions, were reported to alter the nuclear epigenetic landscape. Unbalanced mitoepigenetics and adverse regulation of oxidative phosphorylation (OXPHOS) can efficiently facilitate cancer cell survival. Accordingly, several mitochondria-targeting therapeutic agents (biguanides, OXPHOS inhibitors, vitamin-E analogues, and antibiotic bedaquiline) were suggested for future clinical trials in breast cancer patients. However, crosstalk mechanisms between altered mitoepigenetics and cancer-associated mtDNA mutations remain largely unclear. Hence, mtDNA mutations and epigenetic modifications could be considered as potential molecular markers for early diagnosis and targeted therapy of breast cancer. This review discusses the role of mitoepigenetic regulation in cancer cells and potential employment of mtDNA modifications as novel anti-cancer targets.

Targeting cancer stem cells with antibiotics inducing mitochondrial dysfunction as an alternative anticancer therapy

Traditional cancer treatments based on chemo- and/or radiotherapy effectively kill only differentiated cancer cells, while metastasis and recurrences are caused by surviving cancer resistant cells (CRC) or a special subpopulation of cancer cells known as cancer stem cells (CSC). Both of these cell types compromise anticancer treatment through various mechanisms, including withdrawal of the anticancer drug through ATP-binding cassette transporters, increased expression of DNA repair genes, or transition to a quiescent phenotype. In contrast to many cancers, where energy consumption is due to glycolysis (Warburg effect), the bioenergetics of CSC and CRC is most often related to oxidative phosphorylation, that is, dependent on mitochondrial function. Therefore, compounds that induce mitochondrial dysfunction (MDF), such as some antibiotics, may represent an alternative approach to anticancer therapy. This review summarizes the major recent works on the use of antibiotics to target tumors via CSC and suggests next steps for developing this approach.

Targeting OXPHOS and the electronic transport chain in cancer; molecular and therapeutic implications

Oxidative phosphorylation (OXPHOS) takes place in mitochondria and is the process whereby cells use carbon fuels and oxygen to generate ATP. Formerly OXPHOS was thought to be reduced in tumours and that glycolysis was the critical pathway for generation of ATP but it is now clear that OXPHOS, at least in many tumour types, plays a critical role in delivering the bioenergetic and macromolecular anabolic requirements of cancer cells. There is now great interest in targeting the OXPHOS and the electron transport chain for cancer therapy and in this review article we describe current therapeutic approaches and challenges.

Repurposing non-oncology small-molecule drugs to improve cancer therapy: Current situation and future directions

Drug repurposing or repositioning has been well-known to refer to the therapeutic applications of a drug for another indication other than it was originally approved for. Repurposing non-oncology small-molecule drugs has been increasingly becoming an attractive approach to improve cancer therapy, with potentially lower overall costs and shorter timelines. Several non-oncology drugs approved by FDA have been recently reported to treat different types of human cancers, with the aid of some new emerging technologies, such as omics sequencing and artificial intelligence to overcome the bottleneck of drug repurposing. Therefore, in this review, we focus on summarizing the therapeutic potential of non-oncology drugs, including cardiovascular drugs, microbiological drugs, small-molecule antibiotics, anti-viral drugs, anti-inflammatory drugs, anti-neurodegenerative drugs, antipsychotic drugs, antidepressants, and other drugs in human cancers. We also discuss their novel potential targets and relevant signaling pathways of these old non-oncology drugs in cancer therapies. Taken together, these inspiring findings will shed new light on repurposing more non-oncology small-molecule drugs with their intricate molecular mechanisms for future cancer drug discovery.

Defueling the cancer: ATP synthase as an emerging target in cancer therapy

Reprogramming of cellular metabolism is a hallmark of cancer. Mitochondrial ATP synthase (MAS) produces most of the ATP that drives the cell. High expression of the MAS-composing proteins is found during cancer and is linked to a poor prognosis in glioblastoma, ovarian cancer, prostate cancer, breast cancer, and clear cell renal cell carcinoma. Cell surface-expressed ATP synthase, translocated from mitochondrion to cell membrane, involves the angiogenesis, tumorigenesis, and metastasis of cancer. ATP synthase has therefore been considered a therapeutic target. We review recent various ATP synthase inhibitors that suppress tumor growth and are being tested for the clinic.

The Effect of Tuberculosis Antimicrobials on the Immunometabolic Profiles of Primary Human Macrophages Stimulated with Mycobacterium tuberculosis

Tuberculosis (TB) remains a global health challenge. Patients with drug-sensitive and drug-resistant TB undergo long, arduous, and complex treatment regimens, often involving multiple antimicrobials. While these drugs were initially implemented based on their bactericidal effects, some studies show that TB antimicrobials can also directly affect cells of the immune system, altering their immune function. As use of these antimicrobials has been the mainstay of TB therapy for over fifty years now, it is more important than ever to understand how these antimicrobials affect key pathways of the immune system. One such central pathway, which underpins the immune response to a variety of infections, is immunometabolism, namely glycolysis and oxidative phosphorylation (OXPHOS). We hypothesise that in addition to their direct bactericidal effect on Mycobacterium tuberculosis (Mtb), current TB antimicrobials can modulate immunometabolic profiles and alter mitochondrial function in primary human macrophages. Human monocyte-derived macrophages (hMDMs) were differentiated from PBMCs isolated from healthy blood donors, and treated with four first-line and six second-line TB antimicrobials three hours post stimulation with either iH37Rv-Mtb or lipopolysaccharide (LPS). 24 h post stimulation, baseline metabolism and mitochondrial function were determined using the Seahorse Extracellular Flux Analyser. The effect of these antimicrobials on cytokine and chemokine production was also assayed using Meso Scale Discovery Multi-Array technology. We show that some of the TB antimicrobials tested can significantly alter OXPHOS and glycolysis in uninfected, iH37Rv-Mtb, and LPS-stimulated hMDMs. We also demonstrate how these antimicrobial-induced immunometabolic effects are linked with alterations in mitochondrial function. Our results show that TB antimicrobials, specifically clofazimine, can modify host immunometabolism and mitochondrial function. Moreover, clofazimine significantly increased the production of IL-6 in human macrophages that were stimulated with iH37Rv-Mtb. This provides further insight into the use of some of these TB antimicrobials as potential host-directed therapies in patients with early and active disease, which could help to inform TB treatment strategies in the future.

High ATP Production Fuels Cancer Drug Resistance and Metastasis: Implications for Mitochondrial ATP Depletion Therapy

Recently, we presented evidence that high mitochondrial ATP production is a new therapeutic target for cancer treatment. Using ATP as a biomarker, we isolated the “metabolically fittest” cancer cells from the total cell population. Importantly, ATP-high cancer cells were phenotypically the most aggressive, with enhanced stem-like properties, showing multi-drug resistance and an increased capacity for cell migration, invasion and spontaneous metastasis. In support of these observations, ATP-high cells demonstrated the up-regulation of both mitochondrial proteins and other protein biomarkers, specifically associated with stemness and metastasis. Therefore, we propose that the “energetically fittest” cancer cells would be better able to resist the selection pressure provided by i) a hostile micro-environment and/or ii) conventional chemotherapy, allowing them to be naturally-selected for survival, based on their high ATP content, ultimately driving tumor recurrence and distant metastasis. In accordance with this energetic hypothesis, ATP-high MDA-MB-231 breast cancer cells showed a dramatic increase in their ability to metastasize in a pre-clinical model in vivo. Conversely, metastasis was largely prevented by treatment with an FDA-approved drug (Bedaquiline), which binds to and inhibits the mitochondrial ATP-synthase, leading to ATP depletion. Clinically, these new therapeutic approaches could have important implications for preventing treatment failure and avoiding cancer cell dormancy, by employing ATP-depletion therapy, to target even the fittest cancer cells.

Resveratrol (RV): A pharmacological review and call for further research

Resveratrol (RV) is a well-known polyphenolic compound in various plants, including grape, peanut, and berry fruits, which is quite famous for its association with several health benefits such as anti-obesity, cardioprotective neuroprotective, antitumor, antidiabetic, antioxidants, anti-age effects, and glucose metabolism. Significantly, promising therapeutic properties have been reported in various cancer, neurodegeneration, and atherosclerosis and are regulated by several synergistic pathways that control oxidative stress, cell death, and inflammation. Similarly, RV possesses a strong anti-adipogenic effect by inhibiting fat accumulation processes and activating oxidative and lipolytic pathways, exhibiting their cardioprotective effects by inhibiting platelet aggregation. The RV also shows significant antibacterial effects against various food-borne pathogens (Listeria, Campylobacter, Staphylococcus aureus, and E. coli) by inhibiting an electron transport chain (ETC) and F0F1-ATPase, which decreases the production of cellular energy that leads to the spread of pathogens. After collecting and analyzing scientific literature, it may be concluded that RV is well tolerated and favorably affects cardiovascular, neurological, and diabetic disorders. As such, it is possible that RV can be considered the best nutritional additive and a complementary drug, especially a therapeutic candidate. Therefore, this review would increase knowledge about the blend of RV as well as inspire researchers around the world to consider RV as a pharmaceutical drug to combat future health crises against various inhumane diseases. In the future, this article will be aware of discoveries about the potential of this promising natural compound as the best nutraceuticals and therapeutic drugs in medicine.

Inhalable bedaquiline-loaded cubosomes for the treatment of non-small cell lung cancer (NSCLC)

Non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths globally. Treatment-related adverse effects and development of drug resistance limit the available treatment options for most patients. Therefore, newer drug candidates and drug delivery systems that have limited adverse effects with significant anti-cancer efficacy are needed. For NSCLC treatment, delivering drugs via inhalation is highly beneficial as it requires lower doses and limits systemic toxicity. Bedaquiline (BQ), an FDA-approved anti-tuberculosis drug has previously shown excellent anti-cancer efficacy. However, poor aqueous solubility limits its delivery via the lungs. In this project, we developed inhalable BQ-loaded cubosome (BQLC) nanocarriers against NSCLC. The BQLC were prepared using a solvent evaporation technique with the cubosomal nanocarriers exhibiting a particle size of 150.2 ± 5.1 nm, zeta potential of (+) 35.4 ± 2.3 mV, and encapsulation efficiency of 51.85 ± 4.83%. The solid-state characterization (DSC and XRD) confirmed drug encapsulation and in an amorphous form within the cubosomes. The BQLC nanocarriers showed excellent aerodynamic properties after nebulization (MMAD of 4.21 ± 0.53 µm and FPF > 75%). The BQLC displayed enhanced cellular internalization and cytotoxicity with a ~ 3-fold reduction in IC₅₀ compared to free BQ in NSCLC (A549) cells, after 48 h treatment. The BQLC suppressed cell proliferation via apoptotic pathway, further inhibited colony formation, and cancer metastasis in vitro. Additionally, 3D-tumor simulation studies established the anti-cancer efficacy of cubosomal nanocarriers as compared to free BQ. This is the first study exploring the potential of cubosomes as inhalation therapy of repurposed drug, BQ and the results suggest that BQLC may be a promising NSCLC therapy due to excellent aerosolization performance and enhanced anti-cancer activity.

Neuroprotective Effect of a Novel ATP-Synthase Inhibitor Bedaquiline in Cerebral Ischemia-Reperfusion Injury

Mitochondrial dysfunction during ischemic stroke ultimately manifests as ATP depletion. Mitochondrial ATP synthase upon loss of mitochondrial membrane potential during ischemia rapidly hydrolyses ATP and thus contributes to ATP depletion. Increasing evidence suggests that inhibition of ATP synthase limits ATP depletion and is protective against ischemic tissue damage. Bedaquiline (BDQ) is an anti-microbial agent, approved for clinical use, that inhibits ATP synthase of Mycobacteria; however recently it has been shown to act on mitochondrial ATP synthase, inhibiting both ATP synthesis and hydrolysis in low micromolar concentrations. In this study, we investigated whether preconditioning with BDQ can alleviate ischemia/reperfusion-induced brain injury in Wistar rats after middle cerebral artery occlusion-reperfusion and whether it affects mitochondrial functions. We found that BDQ was effective in limiting necrosis and neurological dysfunction during ischemia-reperfusion. BDQ also caused inhibition of ATPase activity, mild uncoupling of respiration, and stimulated mitochondrial respiration both in healthy and ischemic mitochondria. Mitochondrial calcium retention capacity was unaffected by BDQ preconditioning. We concluded that BDQ has neuroprotective properties associated with its action on mitochondrial respiration and ATPase activity.

Targeting Mitochondrial Oxidative Phosphorylation in Glioblastoma Therapy

As a multi-functional cellular organelle, mitochondrial metabolic reprogramming is well recognized as a hallmark of cancer. The center of mitochondrial metabolism is oxidative phosphorylation (OXPHOS), in which cells use enzymes to oxidize nutrients, thereby converting the chemical energy to the biological energy currency ATPs. OXPHOS also creates the mitochondrial membrane potential and serve as the driving force of other mitochondrial metabolic pathways and experiences significant reshape in the different stages of tumor progression. In this minireview, we reviewed the major mitochondrial pathways that are connected to OXPHOS and are affected in cancer cells. In addition, we summarized the function of novel bio-active molecules targeting mitochondrial metabolic processes such as OXPHOS, mitochondrial membrane potential and mitochondrial dynamics. These molecules exhibit intriguing preclinical and clinical results and have been proven to be promising antitumor candidates in recent studies.

Bedaquiline, an FDA-approved drug, inhibits mitochondrial ATP production and metastasis in vivo, by targeting the gamma subunit (ATP5F1C) of the ATP synthase

Here, we provide evidence that high ATP production by the mitochondrial ATP-synthase is a new therapeutic target for anticancer therapy, especially for preventing tumor progression. More specifically, we isolated a subpopulation of ATP-high cancer cells which are phenotypically aggressive and demonstrate increases in proliferation, stemness, anchorage-independence, cell migration, invasion and multi-drug resistance, as well as high antioxidant capacity. Clinically, these findings have important implications for understanding treatment failure and cancer cell dormancy. Using bioinformatic analysis of patient samples, we defined a mitochondrial-related gene signature for metastasis, which features the gamma-subunit of the mitochondrial ATP-synthase (ATP5F1C). The relationship between ATP5F1C protein expression and metastasis was indeed confirmed by immunohistochemistry. Next, we used MDA-MB-231 cells as a model system to functionally validate these findings. Importantly, ATP-high MDA-MB-231 cells showed a nearly fivefold increase in metastatic capacity in vivo. Consistent with these observations, ATP-high cells overexpressed (i) components of mitochondrial complexes I-V, including ATP5F1C, and (ii) markers associated with circulating tumor cells (CTCs) and metastasis, such as EpCAM and VCAM1. Knockdown of ATP5F1C expression significantly reduced ATP-production, anchorage-independent growth, and cell migration, as predicted. Similarly, therapeutic administration of the FDA-approved drug, Bedaquiline, downregulated ATP5F1C expression in vitro and prevented spontaneous metastasis in vivo. In contrast, Bedaquiline had no effect on the growth of non-tumorigenic mammary epithelial cells (MCF10A) or primary tumors in vivo. Taken together, our results suggest that mitochondrial ATP depletion is a new therapeutic strategy for metastasis prophylaxis, to avoid treatment failure. In summary, we conclude that mitochondrial ATP5F1C is a promising new biomarker and molecular target for future drug development, for the prevention of metastatic disease progression.

Mitochondria as a potential target for the development of prophylactic and therapeutic drugs against Schistosoma mansoni infection

Emergence of parasites resistant to praziquantel, the only therapeutic agent, and its ineffectiveness as a prophylactic agent (inactive against the migratory/juvenile Schistosoma mansoni), makes the development of new antischistosomal drugs urgent. The parasite's mitochondrion is an attractive target for drug development because this organelle is essential for survival throughout the parasite's life cycle. We investigated the effects of 116 compounds against Schistosoma mansoni cercariae motility that have been reported to affect mitochondria-related processes in other organisms. Next, eight compounds plus two controls (mefloquine and praziquantel) were selected and assayed against motility of schistosomula (in vitro) and adults (ex vivo). Prophylactic and therapeutic assays were performed using infected mouse models. Inhibition of oxygen consumption rate (OCR) was assayed using Seahorse XFe24 Analyzer. All selected compounds showed excellent prophylactic activity, reducing the worm burden in the lungs to less than 15% that obtained in the vehicle control. Notably, ascofuranone showed the highest activity with a 98% reduction of the worm burden, suggesting the potential for development of ascofuranone as a prophylactic agent. The worm burden of infected mice with S. mansoni at the adult stage was reduced by more than 50% in mice treated with mefloquine, nitazoxanide, amiodarone, ascofuranone, pyrvinium pamoate, or plumbagin. Moreover, adult mitochondrial OCR was severely inhibited by ascofuranone, atovaquone, and nitazoxanide, while pyrvinium pamoate inhibited both mitochondrial and non-mitochondrial OCRs. These results demonstrate that the mitochondria of S. mansoni are feasible target for drug development.

Potential Therapies Targeting Metabolic Pathways in Cancer Stem Cells

Cancer stem cells (CSCs) are heterogeneous cells with stem cell-like properties that are responsible for therapeutic resistance, recurrence, and metastasis, and are the major cause for cancer treatment failure. Since CSCs have distinct metabolic characteristics that plays an important role in cancer development and progression, targeting metabolic pathways of CSCs appears to be a promising therapeutic approach for cancer treatment. Here we classify and discuss the unique metabolisms that CSCs rely on for energy production and survival, including mitochondrial respiration, glycolysis, glutaminolysis, and fatty acid metabolism. Because of metabolic plasticity, CSCs can switch between these metabolisms to acquire energy for tumor progression in different microenvironments compare to the rest of tumor bulk. Thus, we highlight the specific conditions and factors that promote or suppress CSCs properties to portray distinct metabolic phenotypes that attribute to CSCs in common cancers. Identification and characterization of the features in these metabolisms can offer new anticancer opportunities and improve the prognosis of cancer. However, the therapeutic window of metabolic inhibitors used alone or in combination may be rather narrow due to cytotoxicity to normal cells. In this review, we present current findings of potential targets in these four metabolic pathways for the development of more effective and alternative strategies to eradicate CSCs and treat cancer more effectively in the future.

Potential Therapies Targeting Metabolic Pathways in Cancer Stem Cells

Cancer stem cells (CSCs) are heterogeneous cells with stem cell-like properties that are responsible for therapeutic resistance, recurrence, and metastasis, and are the major cause for cancer treatment failure. Since CSCs have distinct metabolic characteristics that plays an important role in cancer development and progression, targeting metabolic pathways of CSCs appears to be a promising therapeutic approach for cancer treatment. Here we classify and discuss the unique metabolisms that CSCs rely on for energy production and survival, including mitochondrial respiration, glycolysis, glutaminolysis, and fatty acid metabolism. Because of metabolic plasticity, CSCs can switch between these metabolisms to acquire energy for tumor progression in different microenvironments compare to the rest of tumor bulk. Thus, we highlight the specific conditions and factors that promote or suppress CSCs properties to portray distinct metabolic phenotypes that attribute to CSCs in common cancers. Identification and characterization of the features in these metabolisms can offer new anticancer opportunities and improve the prognosis of cancer. However, the therapeutic window of metabolic inhibitors used alone or in combination may be rather narrow due to cytotoxicity to normal cells. In this review, we present current findings of potential targets in these four metabolic pathways for the development of more effective and alternative strategies to eradicate CSCs and treat cancer more effectively in the future.

Effect of the interference with DRP1 expression on the biological characteristics of glioma stem cells

In the present study, a model of glioma stem cells (GSCs) was established and combined with molecular targeting drugs in order to observe its inhibitory effect on the proliferation and biological characteristics of GSCs, with the aim of providing a potential target for the treatment of glioma. On the basis of a relatively classical induction strategy with neuron induction medium, a large number of GSC-like cells in good condition and globular growth were amplified in vitro, which had the potential to differentiate into neurons, oligodendrocytes and astrocytes/glioma cells. It was observed that the interference with dynamin-related protein 1 expression using Mdivi-1, a mitochondrial mitotic inhibitor, at the optimal concentration, decreased the expression level of stem cell-associated genes, inhibited proliferation and promoted apoptosis in GSCs. The present study provided an experimental basis for a novel strategy of cancer treatment with tumor stem cells as the target.

Repurposing Bedaquiline for Effective Non-Small Cell Lung Cancer (NSCLC) Therapy as Inhalable Cyclodextrin-Based Molecular Inclusion Complexes

There is growing evidence that repurposed drugs demonstrate excellent efficacy against many cancers, while facilitating accelerated drug development process. In this study, bedaquiline (BDQ), an FDA approved anti-mycobacterial agent, was repurposed and an inhalable cyclodextrin complex formulation was developed to explore its anti-cancer activity in non-small cell lung cancer (NSCLC). A sulfobutyl ether derivative of β-cyclodextrin (SBE-β-CD) was selected based on phase solubility studies and molecular modeling to prepare an inclusion complex of BDQ and cyclodextrin. Aqueous solubility of BDQ was increased by 2.8 × 10³-fold after complexation with SBE-β-CD, as compared to its intrinsic solubility. Solid-state characterization studies confirmed the successful incorporation of BDQ in the SBE-β-CD cavity. In vitro lung deposition study results demonstrated excellent inhalable properties (mass median aerodynamic diameter: 2.9 ± 0.6 µm (<5 µm) and fine particle fraction: 83.3 ± 3.8%) of BDQ-CD complex. Accelerated stability studies showed BDQ-CD complex to be stable up to 3 weeks. From cytotoxicity studies, a slight enhancement in the anti-cancer efficacy was observed with BDQ-cyclodextrin complex, compared to BDQ alone in H1299 cell line. The IC₅₀ values for BDQ and BDQ-CD complex were found to be ~40 µM in case of H1299 cell line at 72 h, whereas BDQ/BDQ-CD were not found to be cytotoxic up to concentrations of 50 µM in A549 cell line. Taken together, BDQ-CD complex offers a promising inhalation strategy with efficient lung deposition and cytotoxicity for NSCLC treatment.

Triphenilphosphonium Analogs of Chloramphenicol as Dual-Acting Antimicrobial and Antiproliferating Agents

In the current work, in continuation of our recent research, we synthesized and studied new chimeric compounds, including the ribosome-targeting antibiotic chloramphenicol (CHL) and the membrane-penetrating cation triphenylphosphonium (TPP), which are linked by alkyl groups of different lengths. Using various biochemical assays, we showed that these CAM-Cn-TPP compounds bind to the bacterial ribosome, inhibit protein synthesis in vitro and in vivo in a way similar to that of the parent CHL, and significantly reduce membrane potential. Similar to CAM-C4-TPP, the mode of action of CAM-C10-TPP and CAM-C14-TPP in bacterial ribosomes differs from that of CHL. By simulating the dynamics of CAM-Cn-TPP complexes with bacterial ribosomes, we proposed a possible explanation for the specificity of the action of these analogs in the translation process. CAM-C10-TPP and CAM-C14-TPP more strongly inhibit the growth of the Gram-positive bacteria, as compared to CHL, and suppress some CHL-resistant bacterial strains. Thus, we have shown that TPP derivatives of CHL are dual-acting compounds targeting both the ribosomes and cellular membranes of bacteria. The TPP fragment of CAM-Cn-TPP compounds has an inhibitory effect on bacteria. Moreover, since the mitochondria of eukaryotic cells possess qualities similar to those of their prokaryotic ancestors, we demonstrate the possibility of targeting chemoresistant cancer cells with these compounds.

Deletion of the ATP2 Gene in Candida albicans Blocks Its Escape From Macrophage Clearance

Macrophages provide the first-line defense against invasive fungal infections and, therefore, escape from macrophage becomes the basis for the establishment of Candida albicans invasive infection. Here, we found that deletion of ATP2 (atp2Δ/Δ) in C. albicans resulted in a dramatic decrease from 69.2% (WT) to 1.2% in the escape rate in vitro. The effect of ATP2 on macrophage clearance stands out among the genes currently known to affect clearance. In the normal mice, the atp2Δ/Δ cells were undetectable in major organs 72 h after systemic infection, while WT cells persisted in vivo. However, in the macrophage-depleted mice, atp2Δ/Δ could persist for 72 h at an amount comparable to that at 24 h. Regarding the mechanism, WT cells sustained growth and switched to hyphal form, which was more conducive to escape from macrophages, in media that mimic the glucose-deficient environment in macrophages. In contrast, atp2Δ/Δ cells can remained viable but were unable to complete morphogenesis in these media, resulting in them being trapped within macrophages in the yeast form. Meanwhile, atp2Δ/Δ cells were killed by oxidative stress in alternative carbon sources by 2- to 3-fold more than WT cells. Taken together, ATP2 deletion prevents C. albicans from escaping macrophage clearance, and therefore ATP2 has a functional basis as a drug target that interferes with macrophage clearance.

In vitro Antibacterial Activity of an FDA-Approved H+-ATPase Inhibitor, Bedaquiline, Against Streptococcus mutans in Acidic Milieus

Background

Dental caries is an acid-related disease. Current anti-caries agents mainly focus on the bacteriostatic effect in a neutral environment and do not target acid-resistant microorganisms related to caries in acidic milieus.

Objectives

To assess the in vitro antibacterial activities of bedaquiline against oral pathogens in acidic milieus.

Methods

Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius were used to prepare the mono-/multiple suspension and biofilm. The MIC and IC₅₀ of bedaquiline against S. mutans were determined by the broth microdilution method. Bedaquiline was compared regarding (i) the inhibitory activity in pH 4–7 and at different time points against planktonic and biofilm; (ii) the effect on the production of lactic acid, extracellular polysaccharide, and pH of S. mutans biofilm; (iii) the cytotoxicity effects; and (iv) the activity on H⁺-ATPase enzyme of S. mutans.

Results

In pH 5 BHI, 2.5 mg/L (IC₅₀) and 4 mg/L (MIC) of bedaquiline inhibited the proliferation and biofilm generation of S. mutans and Mix in a dose-dependent and time-dependent manner, but it was invalid in a neutral environment. The lactic acid production, polysaccharide production, and pH drop range reduced with the incorporation of bedaquiline in a pH 5 environment. Its inhibitory effect (>56 mg/L) against H⁺-ATPase enzyme in S. mutans and its non-toxic effect (<10 mg/L) on periodontal ligament stem cells were also confirmed.

Conclusion

Bedaquiline is efficient in inhibiting the proliferation and biofilm generation of S. mutans and other oral pathogens in an acidic environment. Its high targeting property and non-cytotoxicity also promote its clinical application potential in preventing caries. Further investigation of its specific action sites and drug modification are warranted.

Cancer Stem Cell Metabolism

Cancer stem cells (CSCs), also known as tumorinitiating cells (TICs), are a group of cells found within cancer cells. Like normal stem cells, CSCs can proliferate, engage in self-renewal, and are often implicated in the recurrence of tumors after therapy [1, 2]. The existence of CSCs in various types of cancer has been proven, such as in acute myeloid leukemia (AML) [3], breast [4], pancreatic [5], and lung cancers [6], to name a few. There are two theories regarding the origin of CSCs. First, CSCs may have arisen from normal stem/progenitor cells that experienced changes in their environment or genetic mutations. On the other hand, CSCs may also have originated from differentiated cells that underwent genetic and/or heterotypic modifications [7]. Either way, CSCs reprogram their metabolism in order to support tumorigenesis.

RP-HPLC method development and validation for bedaquiline fumarate to evaluate its forced degradation behaviour and stability in official dissolution media

Background

A simple, rapid and accurate reverse phase RP-HPLC method for the validation of antitubercular drug bedaquiline fumarate (BQF) was developed. The stability and forced degradation behaviour of bedaquiline fumarate (BQF) in official dissolution media (0.01 N HCl) and methanol were assessed.

Results

The method provided linear responses within the concentration range which varies from 10 to 100 μg/mL with LOD values of 2.6 μg/mL and LOQ of 7.9 μg/mL. Mean percent recovery varied between 97.46 and 103.82% and precise mean RSD of 0.31% (repeatability) and 0.48% (intermediate precision). The method was validated for other parameters like specificity, system suitability and robustness. Potential degradation of the BQF when exposed to direct sunlight in official dissolution media was 90.75% and in methanolic stock solution was 91.98%. Acid-alkali degradation study showed 86.59% loss of BQF in 0.5 N NaOH, and in acidic environment (0.5 N HCl), there was 6.15% loss. Thermal degradation of BQF was 70.11% loss in official dissolution media at 80 °C. No significant change in drug concentrations was noted when exposed and protected from normal daylight at room temperature and at 2–8 °C temperature.

Conclusion

The developed method has significant applicability for the qualitative and quantitative determination of BQF in different pharmaceutical formulations in the official dissolution media in routine quality control analysis.

Why All the Fuss about Oxidative Phosphorylation (OXPHOS)?

Certain subtypes of cancer cells require oxidative phosphorylation (OXPHOS) to survive. Increased OXPHOS dependency is frequently a hallmark of cancer stem cells and cells resistant to chemotherapy and targeted therapies. Suppressing the OXPHOS function might also influence the tumor microenvironment by alleviating hypoxia and improving the antitumor immune response. Thus, targeting OXPHOS is a promising strategy to treat various cancers. A growing arsenal of therapeutic agents is under development to inhibit this biological process. This Perspective provides an overview of the structure and function of OXPHOS complexes, their biological functions in cancer, relevant research tools and models, as well as the limitations of OXPHOS as drug targets. We also focus on the current development status of OXPHOS inhibitors and potential therapeutic strategies to strengthen their clinical applications.

Mitochondrial Fission Factor (MFF) Inhibits Mitochondrial Metabolism and Reduces Breast Cancer Stem Cell (CSC) Activity

Elevated mitochondrial biogenesis and metabolism represent key features of breast cancer stem cells (CSCs), whose propagation is conducive to disease onset and progression. Therefore, interfering with mitochondria biology and function may be regarded as a useful approach to eradicate CSCs. Here, we used the breast cancer cell line MCF7 as a model system to interrogate how mitochondrial fission contributes to the development of mitochondrial dysfunction toward the inhibition of metabolic flux and stemness. We generated an isogenic MCF7 cell line transduced with Mitochondrial Fission Factor (MCF7-MFF), which is primarily involved in mitochondrial fission. We evaluated the biochemical, molecular and functional properties of MCF7-MFF cells, as compared to control MCF7 cells transduced with the empty vector (MCF7-Control). We observed that MFF over-expression reduces both mitochondrial mass and activity, as evaluated using the mitochondrial probes MitroTracker Red and MitoTracker Orange, respectively. The analysis of metabolic flux using the Seahorse XFe96 revealed the inhibition of OXPHOS and glycolysis in MCF7-MFF cells, suggesting that increased mitochondrial fission may impair the biochemical properties of these organelles. Notably, CSCs activity, assessed by 3D-tumorsphere assays, was reduced in MCF7-MFF cells. A similar trend was observed for the activity of ALDH, a well-established marker of stemness. We conclude that enhanced mitochondrial fission may compromise CSCs propagation, through the impairment of mitochondrial function, possibly leading to a quiescent cell phenotype. Unbiased proteomic analysis revealed that proteins involved in mitochondrial dysfunction, oxidative stress-response, fatty acid metabolism and hypoxia signaling are among the most highly up-regulated in MCF7-MFF cells. Of note, integrated analysis of top regulatory networks obtained from unbiased proteomics in MCF7-MFF cells predicts that this cell phenotype activates signaling systems and effectors involved in the inhibition of cell survival and adhesion, together with the activation of specific breast cancer cell death programs. Overall, our study shows that unbalanced and abnormal activation of mitochondrial fission may drive the impairment of mitochondrial metabolic function, leading to inhibition of CSC propagation, and the activation of quiescence programs. Exploiting the potential of mitochondria to control pivotal events in tumor biology may, therefore, represent a useful tool to prevent disease progression.

Co-targeting of lysosome and mitophagy in cancer stem cells with chloroquine analogues and antibiotics

The catabolic autophagy eliminates cytoplasmic components and organelles via lysosomes. Non-selective bulk autophagy and selective autophagy (mitophagy) are linked in intracellular homeostasis both normal and cancer cells. Autophagy has complex and paradoxical dual role in cancers; it can play either tumour suppressor or tumour promoter depending on the tumour type, stage, microenvironment and genetic context. Cancer stem cells (CSCs) cause tumour recurrence and promote resistant to therapy for driving poor clinical consequences. Thus, new healing strategies are urgently needed to annihilate and eradicate CSCs. As chloroquine (CQ) analogues show positive clinical outcome in several clinical trials either standalone or combination with several chemotherapies. Moreover, CQ analogues are known to eliminate CSCs via altering DNA methylation. However, several obstacles such as higher concentrations and dose-dependent toxicity are noticeable in the treatment of cancers. As tumour cells predominantly rely on mitochondrial actions, mitochondrial targeting FDA-approved antibiotics are reported to effectively eradicate CSCs alone or combination with chemotherapy. However, antibiotics cause metabolic glycolytic shift in cancer cells for survival and repopulation. This review will provide a sketch of the inhibiting roles of current chloroquine analogues and antibiotic combination in CSC autophagy process and discuss the possibility that pre-clinical and clinical potential therapeutic strategy for anticancer therapy.

Understanding and Exploiting the Effect of Tuberculosis Antimicrobials on Host Mitochondrial Function and Bioenergetics

Almost 140 years after its discovery, tuberculosis remains the leading infectious cause of death globally. For half a century, patients with drug-sensitive and drug-resistant tuberculosis have undergone long, arduous, and complex treatment processes with several antimicrobials that primarily function through direct bactericidal activity. Long-term utilization of these antimicrobials has been well-characterized and associated with numerous toxic side-effects. With the prevalence of drug-resistant strains on the rise and new therapies for tuberculosis urgently required, a more thorough understanding of these antimicrobials is a necessity. In order to progress from the “one size fits all” treatment approach, understanding how these antimicrobials affect mitochondrial function and bioenergetics may provide further insight into how these drugs affect the overall functions of host immune cells during tuberculosis infection. Such insights may help to inform future studies, instigate discussion, and help toward establishing personalized approaches to using such antimicrobials which could help to pave the way for more tailored treatment regimens. While recent research has highlighted the important role mitochondria and bioenergetics play in infected host cells, only a small number of studies have examined how these antimicrobials affect mitochondrial function and immunometabolic processes within these immune cells. This short review highlights how these antimicrobials affect key elements of mitochondrial function, leading to further discussion on how they affect bioenergetic processes, such as glycolysis and oxidative phosphorylation, and how antimicrobial-induced alterations in these processes can be linked to downstream changes in inflammation, autophagy, and altered bactericidal activity.

Targeting the Mitochondrial Metabolic Network: A Promising Strategy in Cancer Treatment

Metabolic reprogramming is a hallmark of cancer, which implements a profound metabolic rewiring in order to support a high proliferation rate and to ensure cell survival in its complex microenvironment. Although initial studies considered glycolysis as a crucial metabolic pathway in tumor metabolism reprogramming (i.e., the Warburg effect), recently, the critical role of mitochondria in oncogenesis, tumor progression, and neoplastic dissemination has emerged. In this report, we examined the main mitochondrial metabolic pathways that are altered in cancer, which play key roles in the different stages of tumor progression. Furthermore, we reviewed the function of important molecules inhibiting the main mitochondrial metabolic processes, which have been proven to be promising anticancer candidates in recent years. In particular, inhibitors of oxidative phosphorylation (OXPHOS), heme flux, the tricarboxylic acid cycle (TCA), glutaminolysis, mitochondrial dynamics, and biogenesis are discussed. The examined mitochondrial metabolic network inhibitors have produced interesting results in both preclinical and clinical studies, advancing cancer research and emphasizing that mitochondrial targeting may represent an effective anticancer strategy.

Bedaquiline inhibits the yeast and human mitochondrial ATP synthases

Bedaquiline (BDQ, Sirturo) has been approved to treat multidrug resistant forms of Mycobacterium tuberculosis. Prior studies suggested that BDQ was a selective inhibitor of the ATP synthase from M. tuberculosis. However, Sirturo treatment leads to an increased risk of cardiac arrhythmias and death, raising the concern that this adverse effect results from inhibition at a secondary site. Here we show that BDQ is a potent inhibitor of the yeast and human mitochondrial ATP synthases. Single-particle cryo-EM reveals that the site of BDQ inhibition partially overlaps with that of the inhibitor oligomycin. Molecular dynamics simulations indicate that the binding mode of BDQ to this site is similar to that previously seen for a mycobacterial enzyme, explaining the observed lack of selectivity. We propose that derivatives of BDQ ought to be made to increase its specificity toward the mycobacterial enzyme and thereby reduce the side effects for patients that are treated with Sirturo.

Luo, Zhou et al. show that Bedaquiline (BDQ, Sirturo), approved to treat multi-drug-resistant tuberculosis, inhibits the yeast and human mitochondrial ATP synthases in addition to its intended target, the Mycobacterium tuberculosis ATP synthase. The structure of the mitochondrial ATP synthase bound to BDQ suggests a means to modify this inhibitor to increase its specificity for the M. tuberculosis  enzyme, thereby reducing its side effects for patients.

Cancer stem cells and nanomedicine: new opportunities to combat multidrug resistance?

'Multidrug resistance' (MDR) is a difficult challenge for cancer treatment. The combined role of cytochrome P450 enzymes (CYPs) and active efflux transporters (AETs) in cancer cells appears relevant in inducing MDR. Chemotherapeutic drugs can be substrates of both CYPs and AETs and CYP inducers or inhibitors can produce the same effects on AETs. In addition, a small subpopulation of cancer stem-like cells (CSCs) appears to survive conventional chemotherapy, leading to recurrent disease. Natural products appear efficacious against CSCs; their combinational treatments with standard chemotherapy are promising for cancer eradication, in particular when supported by nanotechnologies.

Cholesterol and Mevalonate: Two Metabolites Involved in Breast Cancer Progression and Drug Resistance through the ERRα Pathway

Breast cancer is the second greatest cause of cancer-related death in women. Resistance to endocrine treatments or chemotherapy is a limiting drawback. In this context, this work aims to evaluate the effects of cholesterol and mevalonate during tumor progression and their contribution in the onset of resistance to clinical treatments in use today. In this study, we demonstrated that cholesterol and mevalonate treatments were able to activate the estrogen-related receptor alpha (ERRα) pathway, increasing the expression levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), ERbB2/human epithelial receptor (HER2), tumor protein D52 (TPD52), and NOTCH2 proteins in breast cancer cells. The activation of this pathway is shown to be responsible for intense metabolic switching, higher proliferation rates, sustained motility, the propagation of cancer stem-like cells (CSCs), and lipid droplet formation. All of these events are related to greater tumor propagation, aggressiveness, and drug resistance. Furthermore, the activation and expression of proteins induced by the treatment with cholesterol or mevalonate are consistent with those obtained from the MCF-7/TAMr cell line, which is largely used as a breast cancer model of acquired endocrine therapy resistance. Altogether, our data indicate that cholesterol and mevalonate are two metabolites implicated in breast cancer progression, aggressiveness, and drug resistance, through the activation of the ERRα pathway. Our findings enable us to identify the ERRα receptor as a poor prognostic marker in patients with breast carcinoma, suggesting the correlation between cholesterol/mevalonate and ERRα as a new possible target in breast cancer treatment.

Role of Mitochondria in Cancer Stem Cell Resistance

Cancer stem cells (CSC) are associated with the mechanisms of chemoresistance to different cytotoxic drugs or radiotherapy, as well as with tumor relapse and a poor prognosis. Various studies have shown that mitochondria play a central role in these processes because of the ability of this organelle to modify cell metabolism, allowing survival and avoiding apoptosis clearance of cancer cells. Thus, the whole mitochondrial cycle, from its biogenesis to its death, either by mitophagy or by apoptosis, can be targeted by different drugs to reduce mitochondrial fitness, allowing for a restored or increased sensitivity to chemotherapeutic drugs. Once mitochondrial misbalance is induced by a specific drug in any of the processes of mitochondrial metabolism, two elements are commonly boosted: an increment in reactive nitrogen/oxygen species and, subsequently, activation of the intrinsic apoptotic pathway.